Conventionally, in a tire air or pneumatic pressure monitoring device such as that described in Japanese Patent Application Publication No. 2010-122023, by transmitting tire pressure monitoring system (TPMS) data at a timing at which an acceleration in a rotational direction of a TPMS sensor installed on each wheel reaches 1 [G] or “−1” [G], a TPMS sensor transmits the TPMS data at a constant rotational position of a wheel. A TPMS control unit installed on a side of a vehicle body determines a wheel position of the TPMS sensor based on the number of teeth that are acquired from a chain of wheel speed pulses detected by a wheel speed sensor at a timing at which the TPMS data has been received.
According to the prior art described above, however, although it is necessary to detect an acceleration in a rotating direction at a predetermined sampling cycle or period, when this sampling period is short, the power consumption of the TPMS sensor will be larger and the long life of the TPMS sensor battery will not be secured, whereas, when the sampling cycle is long, the detection accuracy in the rotational direction will be worse so that there has been a problem that the TPMS sensor (tire air pressure transmission device) cannot send the TPMS data (tire air pressure information) at a constant rotational position of wheel.